Dermatology: Practical and Conceptual Letter | Dermatol Pract Concept 2020;10(3):e2020065 1 Dermatology Practical & Conceptual Introduction Tinea nigra is a rare superficial phaeohyphomycosis whose characteristic lesion is an asymptomatic, unilateral, well-de- limited brown to black macule. Differential diagnoses are melanocytic lesions, subcorneal hemorrhage, and exogenous pigmentation. We present 2 cases of tinea nigra where der- moscopy was helpful in making the correct diagnosis. Case Presentations An 8-year-old girl presented with a well-defined brown patch on the right palm (Figure 1A). Dermoscopy showed homo- geneous “brown spicules” that did not follow the dermato- glyphic lines (Figure 2A). A 5-year-old boy presented with an irregular patch on the left palm (Figure 1B). Dermoscopy showed “brown spicules” following the parallel ridge pattern (Figure 2B). Both patients were from Porto Alegre, Brazil, and had the lesions for approximately 8 months. Mycological exam- ination showed dematiaceous septate hyphae (Figure 3), and Hortaea werneckii was identified in culture. Both patients were treated with fenticonazole cream for 30 days and showed clinical improvement. Conclusions Tinea nigra is a superficial fungal infection that affects the stratum corneum. It is characterized by a single unilateral and asymptomatic brown to black patch that affects mainly the palms and, less frequently, the soles of young adults. It is caused by H. werneckii, a dematiaceous fungus found in tropical and subtropical climates, mainly in the sand at the beach. Mycological examination shows brown and septate hyphae with thick walls. Examination of the culture shows black, humid, and shiny colonies. Clinically, tinea nigra can mimic benign and malignant acral melanocytic lesions. However, pigmented melano- cytic nevi show a parallel furrow pattern that is not seen in tinea nigra. The dermoscopy pattern for tinea nigra was first described as “pigmented spicules,” which form an almost reticulated Entodermoscopy in the Diagnosis of Tinea Nigra: Two Case Reports Manuela Lima Dantas,1 Giovana Serrão Fensterseifer,1 Paulo Henrique Martins,2 Irina A. Paipilla Hernandez,1 Fernando Eibs Cafrune2 1 Dermatology, Porto Alegre, Brazil 2 Dermatology Department, Santa Casa Hospital de Porto Alegre, Brazil Key words: entodermoscopy, superficial mycosis, tinea nigra, melanocytic lesions Citation: Lima Dantas M, Serrão Fensterseifer G, Henrique Martins P, Paipilla Hernandez IA, Eibs Cafrune F. Entodermoscopy in the diagnosis of tinea nigra: two case reports. Dermatol Pract Concept. 2020;10(3):e2020065. DOI: https://doi.org/10.5826/dpc.1003a65 Accepted: April 17, 2020; Published: June 29, 2020 Copyright: ©2020 Lima Dantas et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: None. Competing interests: The authors have no conflicts of interest to disclose. Authorship: All authors have contributed significantly to this publication. Corresponding author: Dr. Giovana Serrão Fensterseifer, Rua Anita Garibaldi, 1143/1203, Porto Alegre, Brazil. Email: gfensterseifer@ gmail.com https://doi.org/10.5826/dpc.1003a65 mailto:gfensterseifer@gmail.com mailto:gfensterseifer@gmail.com 2 Letter | Dermatol Pract Concept 2020;10(3):e2020065 patch [1]. However, Noguchi et al recently described cases of tinea nigra with the parallel ridge pattern, featuring fine, wispy, brown “spicules” (characteristic of tinea nigra) and no color gradation (important clue for differentiation from melanoma) [2]. Besides melanocytic lesions, we have to con- sider subcorneal hematoma and exogenous pigmentation as differential diagnoses. Dermoscopy of subcorneal hematoma usually reveals reddish black homogeneous areas, often accompanied by satellite globules. In doubtful cases, a scrap- ing test can be performed; gentle scraping off of the stratum corneum with a scalpel will result in partial or complete removal of the pigmentation in cases of subcorneal hema- toma. Exogenous pigmentation can present as a parallel ridge pattern on dermoscopy. Previous exposition to some kind of material that can pigment the area, pigmentation favoring foot pressure points, and disappearance within 1 month are important clues for the correct diagnosis (Table 1). Table 1. Dermoscopy Findings of Tinea Nigra and Its Differential Diagnosis Tinea nigra “Pigmented spicules” forming an almost reticulated patch or arranged in parallel ridge pattern with no color gradation Benign acral melanocytic lesion Parallel furrow pattern, fibrillar pattern, or lattice-like pattern Malignant acral melanocytic lesion Parallel ridge pattern Subcorneal hematoma Reddish black homogeneous areas, satellite globules; partial or complete removal of pigment with scrapping test Exogenous pigmentation Parallel ridge pattern; correlate with medical history clues Figure 1. A brown, well-delimited patch on the palm. Figure 3. Mycological examination: demati- aceous septate and branched hyphae.Figure 2. (A) “Brown spicules” forming an almost reticulated patch. (B) “Brown spicules” arranged in the parallel ridge pattern. Letter | Dermatol Pract Concept 2020;10(3):e2020065 3 References 1. Kaminska-Winciorek G, Spiewak R. Tips and tricks in the dermos- copy of pigmented lesions. BMC Dermatol. 2012;12:14. https:// doi.org/10.1186/1471-5945-12-14 2. Noguchi H, Hiruma M, Inoue Y, Miyata K, Tanaka M, Ihn H. Tinea nigra showing a parallel ridge pattern on dermoscopy. J Dermatol. 2015;42(5):518-520. https://doi.org/10.1111/1346- 8138.12830 We present 2 cases of tinea nigra, one with the classic dermoscopy of “brown spicules” forming an almost reticu- lated patch and the other with the most recent dermoscopy pattern described, the parallel ridge pattern, featuring “brown spicules” and no color gradation. Dermoscopy, a noninvasive technique broadly used in the evaluation of pigmented lesions, has shown to be a useful tool for the diagnosis of tinea nigra. https://doi.org/10.1186/1471-5945-12-14 https://doi.org/10.1186/1471-5945-12-14 https://doi.org/10.1111/1346-8138.12830 https://doi.org/10.1111/1346-8138.12830